AB0720 DEVELOPMENT OF RESPONSE CRITERIA FOR GCA: AN SLR INFORMING AN INTERNATIONAL TASK FORCE
Authors: C. Sanchez-Alvarez, M. Bond, M. Soowamber, D. Camellino, M. Anderson, C. Langford, C. Dejaco, Z. Touma, S. Ramiro
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Giant cell arteritis (GCA) is the most common form of large vessel vasculitis. While remission and relapse are common primary endpoints in randomized clinical trials (RCTs), a definition of response is missing. We conducted a systematic literature review (SLR) to inform an international task force developing new response criteria in GCA. <h3>Objectives</h3> To identify descriptors used to measure response to treatment and change of disease activity in GCA in RCTs and longitudinal observational studies (LOS). <h3>Methods</h3> An SLR was conducted using Ovid Medline, Embase, and Cochrane Central. The research question was formulated according to the PICO framework: the population included patients with GCA, any intervention or comparator was considered, and the outcomes addressed were active disease, improvement/response, remission, worsening, relapse, flare, or recurrence. RCTs and LOS with &gt; 20 subjects and studies on qualitative research were included. Titles screening and full data extraction were performed by 2-3 reviewers. Discordant cases were discussed among reviewers until a final consensus; if not achieved, a methodologist was consulted. In case of multiple publications from the same trial and LOS, they were only considered if separate, pre-specified outcomes were reported. <h3>Results</h3> 10,593 studies were retrieved in the search, of which 116 were finally included. The descriptors used for the different outcomes' definition were extracted and grouped into different categories (Figure 1). Active disease was reported in 11/11 (100%) RCTs and 20/104 (19%) LOS. Active disease was predominantly defined as a combination of clinical and laboratory components. The clinical component was described as the presence of symptoms of GCA while the laboratory component mainly included ESR and CRP. Remission was reported in 8/11 (73%) RCTs and 44/104 (42%) LOS. Remission was predominantly defined as a combination of clinical and laboratory components. The clinical component was described as the resolution of clinical signs/symptoms of GCA. The laboratory component (ESR/CRP) was only considered when associated with the resolution of signs/symptoms of GCA. Relapse was reported in 11/11 (100%) RCTs and 90/104 (87%) LOS. Relapse was predominantly defined as a combination of clinical, laboratory and treatment components. The clinical component was defined as the recurrence of clinical signs/symptoms of GCA. The laboratory component included the elevation of ESR and/or CRP. The treatment component (reinstitution or increase in glucocorticoids dose) was frequently considered as a criterion for relapse. No standardized definition of response was found across studies. Most RCTs used composite endpoints (including treatment tapering/discontinuation, maintenance of remission, and absence of relapse over a certain time frame) to assess the primary endpoint – response. Fourteen imaging studies were analyzed (10 prospective and 4 retrospectives). PET-CT was the most studied imaging (n= 10), followed by ultrasound (n=3). PET activity was evaluated thorough qualitative or semiquantitative scores. Ultrasound evaluated presence of disease activity based on the intimal wall thickness/halo sign. <h3>Conclusion</h3> The results of this SLR showed that an internationally accepted definition of response in GCA is elusive so far. RCTs and LOS mainly defined the extremes of the spectrum of GCA disease activity (remission and relapse) as primary endpoints. The descriptors identified will be incorporated in future phases of an international task force for the development of response criteria for GCA. <h3>REFERENCES:</h3> NIL. <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> Catalina Sanchez-Alvarez: None declared, Milena Bond: None declared, Medha Soowamber: None declared, Dario Camellino: None declared, Melanie Anderson: None declared, Carol Langford Consultant of: Bristol Myers Squibb, Grant/research support from: Bristol Myers Squibb, GlaxoSmithKline, and Genentech., Christian Dejaco Speakers bureau: Abbvie, Eli Lilly, Janssen, Novartis, Pfizer, Roche, Galapagos and Sanofi, Consultant of: Abbvie, Eli Lilly, Janssen, Novartis, Pfizer, Roche, Galapagos, Sparrow and Sanofi, Grant/research support from: AbbVie, Zahi Touma Consultant of: gsk, AstraZeneca, Lilly, Merck and Ucb, Sofia Ramiro Grant/research support from: AbbVie, Eli LIlly, Galapagos, MSD, Novartis, Pfizer, Sanofi, UCB.